A frame of the above-mentioned type is disclosed in U.S. Pat. No. 4,636,105 in the name of the present inventor. As shown in FIG. 1 of said document, the frame consists of a top arrangement and a plurality of side members. The top arrangement and side members are linked together by removable corner pieces to form an enclosing frame. The side members are each provided with a groove which is intended to receive edge portions of a rigid display sheet. The top arrangement presents a slot to allow the rigid display sheet to be slid into the grooves in the frame.
The above-described type of frame has proved to be very popular, not least because the corner pieces can be removed to thereby allow the frame to be disassembled for ease of storage and transportation. When assembled, the frame defines an opening in which, for example, a display sheet can be accommodated. The display sheet must be sufficiently rigid so that it will not flex to an extent where its edge portions come out of the grooves, otherwise the sheet could fall out of the frame. This need for a rigid sheet implies that, although the frame can be easily dismantled, the rigid sheet will always present a certain fixed surface area, thereby hindering transportation. When such a frame is used to display a poster, the poster must be supported by a rigid backing element, the edge portions of which are received in the grooves in the side members. Consequently, the frame and backing element are sold as a unit.